Steady-state migration of the liquid film along a grain boundary during melting of alloys

We discuss melting of alloys along grain boundaries as a free boundary problem for two moving solid–liquid interfaces. One of them is the melting front and the other is the solidification front. The presence of the triple junction plays an important role in controlling the velocity of this process. The interfaces interact strongly via the diffusion field in the thin liquid layer between them. In the liquid film migration (LFM) mechanism the system chooses a more efficient kinetic path, which is controlled by diffusion in the liquid film over relatively short distances. However, only weak coherency strain energy is the effective driving force for LFM in the case of melting of one-phase alloys. The process with only one melting front would be controlled by the very slow diffusion in the mother solid phase over relatively large distances.